Description: At a time of great political paralysis around climate change internationally -- and apparent backtracking by American politicians and the public on the science of global warming itself -- there are "reasons to rethink our approach," says moderator John Reilly. He hopes to "create a civil discourse that helps us understand better the varied concerns of people on the topic."

Panelists sketch the past, present and future of climate change. Kerry Emanuel reviews the science of climate change, noting that the greenhouse effect discovery dates back to the 18th century, and that by the end of the 19th, scientists had already begun worrying that consumption of fossil fuel and the accompanying release of CO2 would lead to an increase in surface temperatures of 5-6 degrees C. Modern science with its ice core measurements has tracked dramatic temperature changes on earth over tens of millions of years. But the last 100 years have been unprecedented, with the famous hockey stick illustration capturing the connection between human industry and increased CO2 release. When scientists run some models forward, they show temperature increases ranging from 1.5 to 4çC. While these projections contain uncertainty, says Emmanuel, "this does not mean we should do nothing."

Diverse climate change reconstructions agree: the warmest years of the past century were 1998, 2005 and 2010. "This is happening in real"time," says Ronald Prinn, and whether or not "Florida has a cold winter," warming is occurring "at a rate that should worry us all." The amount of heat the earth absorbs is simply much greater than it can bounce back into space, courtesy of greenhouse gas already accumulated in the atmosphere, and increasingly, by the secondary impacts of climate change such as the melting of ice sheets. At MIT, Prinn's group runs models that factor in clouds, ocean mixing, and varying levels of greenhouse gas emissions. In a "business as usual" model, with no real efforts to rein in fossil fuel use, Prinn puts the risk of a temperature increase higher than 4çC at 85%. If we manage to stabilize CO2 emissions at 550 parts per million (we're at 472 today), there is still a 25% chance of getting greater than 2çC change. Prinn worries about the instability of the arctic tundra and permafrost, which stores 200 times the amount of current human emissions in carbon, as well as the acidification of oceans, placing plankton, basis of all ocean life, at risk.

Against this bleak backdrop, MIT newcomer Chris Knittel describes the policy options for tackling climate change. He acknowledges the "dismal and frustrating science" of environmental economics, which had counted on the equivalent of a carbon tax to discourage carbon emissions, only to meet a wall of political rejection. Carbon pricing lowers demand for the fuel intensive products that matter the most in climate change, and whether in the form of cap and trade, or a direct tax, also spurs technologies aimed at fuel efficiency or encouraging alternative fuels. The nation's fuel standards, set to rise to 35.5 mpg by 2016 are modest, believes Knittel, and subsidies seem to encourage carbon intensive activities rather than reducing them (nb:corn and cellulosic ethanol). States like California are more ambitious, but recent court rulings blocked its cap and trade policy "for environmental justice reasons."

"The question is whether we can substantially decrease energy and carbon intensity while accommodating economic growth," says Ernest Moniz. New technologies that emerge must drive the cost of carbon "very, very low" if they are to make a major impact. With cheap coal the primary fuel generating electricity in the U.S., Moniz offers a "Michelin guide type rating" of possible alternative, 'carbon"free' fuels: At the top are renewables such as solar; nuclear; and coal with capture and sequestration. Natural gas doesn't really figure, since it does not wean society effectively from carbon. Moniz believes the best fuel technologies require substantial innovations to bring down their prices. The nuclear industry may want to try small modular reactors of 50"300 megawatts, rather than the 1600 megawatt behemoths that after Fukushima, are even more controversial. Carbon capture and sequestration will require brand new approaches and full"scale testing. Moniz believes solar technology is making the most rapid progress, specifically in silicon photovoltaics, courtesy in part of work in novel materials at MIT. Also, the "global, peanut"sized industry" of batteries may play a "huge role in transforming the picture" of electric vehicles, possibly making them economically feasible in a decade."

Sarah Slaughter believes the incredible challenge of climate change might make possible wholesale transformation of infrastructure, energy, and other resource systems. She cites New York City's planning efforts to adapt to sea level rise, which would likely flood the sewer system. All communities must think ahead, for hurricanes, or other disasters likely to flow from warming, but rather than replicate what exists today, says Slaughter, planners should focus on "building the world we want to live in." MIT and its partners around the world hope to develop "ground breaking technologies" to help transform communities and make them safer, and healthier. Slaughter envisions solutions such as district"wide heating and cooling, and describes a system introduced in Kenya that converts agricultural waste into fuel for cooking food. "There is an opportunity to do things right as we move forward," she concludes.

About the Speaker(s): Energy, environmental, and agricultural economist John Reilly focuses on understanding the role of human activities as a contributor to global environmental change and the effects of environmental change on society and the economy. A key element of his work is the integration of economic models of the global economy as it represents human activity with models of biophysical systems including the ocean, atmosphere, and terrestrial vegetation. By understanding the complex interactions of human society with our planet, the goal is to aid in the design of policies that can effectively limit the contribution of human activity to environmental change, to facilitate adaptation to unavoidable change, and to understand the consequences of the deployment of large scale energy systems that will be needed to meet growing energy needs.

Host(s): School of Science, MIT Energy Initiative

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Fri, 16 Dec 2011 19:05:57 -0500http://techtv.mit.edu/videos/16795-rethinking-climate-change-the-past-150-years-and-the-next-100-years
http://techtv.mit.edu/videos/16795-rethinking-climate-change-the-past-150-years-and-the-next-100-years
Rethinking Climate Change: The Past 150 Years and the Next 100 Years
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